S•-^!l^^^^~ 



Kinematics of Mechanisms 

 FROM THE Time of Watt 



by Eugene S Ferguson 



MUS. COMP. ZOOL. 

 LIBRARY 



APR 1 6 1963 



HARVARD 

 UNIVERSITY 



In an inventive tour de force that seldom, if ever, has been 

 equalled for its brilliance and far-reaching consequences, James 

 Watt radically altered the steam engine not only by adding a 

 separate condenser but by creati^ig a ivhole new family of linkages. 

 His approach was largely empirical, as ive use the word today. 



This study suggests that, despite the glamor of today's so- 

 phisticated methods of calculation, a highly developed intui- 

 tive sense, reinforced by a knowledge of the past, is still indis- 

 pensable to the design of successful mechanisms. 



The Author: Eugene S. Ferguson, formerly curator of 

 tnechanical and civil engineering in the United States National 

 M.useum, Smithsonian Institution, is now professor of mechan- 

 ical engineering at Iowa State University of Science and Tech- 

 nology . 



In engineering schools today, a student is intro- 

 duced to the kinematics of mechanisms by means of 

 a course of kinematic analysis, which is concerned 

 with principles underlying the motions occurring in 

 mechanisms. These principles are demonstrated by 

 a study of mechanisms already in existence, such as 

 the linkage of a retractable landing gear, computing 

 mechanisms, mechanisms used in an automobile, and 

 the like. A systematic, if not rigorous, approach to 

 the design of gears and cams also is usually presented 

 in such a course. Until recently, however, no serious 

 attempt was made to apply the principles developed 

 in kinematic analysis to the more complex problem 

 of kinematic synthesis of linkages. By kinematic 

 synthesis is meant the designing of a linkage to pro- 

 duce a given series of motions for a particular purpose. 



That a rational — numerical or geometrical — ap- 

 proach to kinematic synthesis is possible is a relatively 

 recent idea, not yet fully accepted; but it is this idea 

 that is responsible for the intense scholarly interest in 

 the kinematics of mechanisms that has occurred in 

 this country within the last 10 years. 



This scholarly activity has resulted in the rediscovery 

 of many earlier works on the subject, and nearly all 

 the .scholars now working in this field have acknowl- 



edged in one way or another their debt to those who 

 arrived on the scene at an earlier time than they. 

 There have been occasional reviews of the sequence 

 and nature of developments, but the emphasis 

 naturally has been upon the recent past. It seems 

 to me that there is something to be gained in looking 

 beyond our own generation, or even beyond the 

 time of Franz Reuleaux (1829-1905), who is gen- 

 erally credited with originating many of our modern 

 concepts of mechanism analysis and design, and to 

 inquire into the ideas that made possible Reuleaux's 

 contributions. 



While no pretense of completeness is made, I have 

 tried in this paper to trace the high points in the 

 developm.ent of kinematic analysis and synthesis, 



Take to Kinematics. It will 

 repay you. It is more fecund 

 than geometry; it adds a fourth 

 dimension to space. 



— Chebyshev to Sylvester, 1873 



186 



BULLETIN 228: CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY 



